Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 119

alternative fuels FT1 and FT2 and their 50 % blends with JP 8) produce similar
results. The minimum engine fuel fl flow operation shows a wide scatter in the com-

bustion ef 99.0 %) that needs to be explained, for which we turn to

the publicly available ICAO engine emission database, a source of certi

ciency (viz. 95.5 -

ed emis-
sions data of all the commercial propulsion engines subject to the ICAO regulatory
NO x standards described in Sect. 2.4 . The CFM56-2/3 class of engine models cover
the ICAO takeoff thrust ranging between 82 and 107 kN with the corresponding
OPR between 21 and 26. Their idle emission indices of HC and CO range between
1.1 and 2.9, 24 and 38, respectively, with the corresponding idle ef ciency ranging

between 99.3 and 98.8 %. Their data for idle CO and HC is represented well by
EIHC idle ¼ 0 : 1178EICO idle 1 : 7351 which is indistinguishable from the data of the

most recent GE ' s rich domes. Therefore for a well-designed modern rich domes,

combustion ef ciency levels along the engine operating lines do not need to be

improved, and one should not seek any guidance from the modeling community on
CO and HC (and therefore combustion ef ciency) as expressed in Table 3 except for

the lean domes where we have a formidable challenge for demonstrating designs that
meet simultaneously combustion ef ciency and high-power NO x requirements; the

latter is discussed extensively in this article.

Table 3 Assess the adequacy of current turbulent combustion models to predict quantities of
interest to industry

Can certain quantities be predicted signi cantly better than others? Which ones?
Prepared by M.S. Anand for the MACCCR workshop (2011)